Air circuit breakers as described within U.S. Pat. No. 3,095,489 entitled "Manual Charging Means for Stored Energy Closing Mechanisms of Electric Circuit Breakers" and U.S. Pat. No. 3,084,238 entitled "Ratchet Mechanism for Charging a Closing Spring in an Electric Circuit Breaker" include operating mechanisms that are mainly exposed to the environment. Since the air circuit breakers are rated to carry several thousand amperes of current continuously, the exposure to convection cooling air assists in keeping the operating components within reasonable temperature limits.
Such air circuit breakers are usually provided with a motor operator such as described in U.S. Pat. No. 4,167,988 entitled "Ratcheting Mechanism for Circuit Breaker Motor Operator" or a manual handle as described in U.S. Pat. No. 3,729,065 entitled "Means for Charging A Stored Energy Circuit Breaker Closing Device" for charging the powerful closing springs contained within the air circuit breaker operating mechanism.
When the circuit breaker closing springs are brought to their fully-charged conditions, it is important that the springs do not become inadvertently discharged while an operator has hold of the charging handle in order to avoid damage to the ratchet mechanism and the associated air circuit breaker contacts. An early arrangement of a latching means to prevent rotation of a closing springs charging handle is found in U.S. Pat. No. 4,475,021 entitled "Air Circuit Breaker".
As the circuit breaker operating handle is pumped to provide the necessary charging force to the circuit breaker closing springs, the torque reflected back to the operating handle increases in proportion to the closing spring forces. Also added to this operating force is the torque generated by the handle return spring per se.
It would be beneficial to an operator to be able to provide charging forces to the circuit breaker closing springs without having to overcome the large forces that are being generated by the handle return spring.
One purpose of the invention, accordingly, is to provide a modular assembly that can be attached to the circuit breaker in the vicinity of the operating handle, both during factory assembly as well as on-site, to maintain a constant low circuit breaker closing spring charging force to the circuit breaker operating handle by reducing the torque requirement of the handle return spring in a manner that does not impede the ability of the return spring from sufficiently returning and holding the operating handle in its home position.